DUBAI, UNITED ARAB EMIRATES, SEPT. 13 -- As U.N. Secretary General Javier Perez de Cuellar moved from Tehran to Baghdad, Iran demanded again today that Iraq be blamed and punished for starting the Persian Gulf war.

Perez de Cuellar arrived in Baghdad after concluding two days of talks in Tehran in search of compliance with the U.N. Security Council's demand for a cease-fire.

The call for labeling Iraq as the aggressor in the seven-year-old gulf conflict has been a persistent undercurrent in Iran's approach to the cease-fire called for in U. N. Security Council Resolution 598.

Before departing for Iraq, Perez de Cuellar met with Iranian President Ali Khamenei. Tehran Radio quoted Khamenei as telling him that "only if Iraq is punished as the aggressor can the talks go forward."

In reference to the Allied war crimes tribunal that tried leading Nazis at the end of World War II, Khamenei said, "No peace-seeking group criticized the establishment of the Nuremberg trials. This trend is accepted by the world. The only formula that can be accepted by the Iranian nation is one which foresees the punishment of the aggressor."

The consistent Iranian demand to punish Iraq for the conflict would appear to place a considerable hurdle in the secretary general's path as he seeks a way to implement the Security Council resolution.

But upon arriving in Baghdad, Perez de Cuellar told reporters that "so far I am neither pessimistic nor optimistic" after his talks in Iran, according to The Associated Press. He said he could not be more specific about his discussions in Tehran until after briefing the Security Council Thursday.

Political observers in the gulf region were divided on the importance of the latest Iranian public position. Some pointed out that the current posture is less rigid than earlier demands for the removal of Iraqi President Saddam Hussein and the payment by Iraq of billions of dollars in war reparations.

While these positions could reemerge, they have not figured in Iran's public commentaries and statements of the past several weeks. These observers point out that any significant Iranian shift also probably be masked by a barrage of rhetoric.

Others say the Iranian insistence on the labeling and the Nuremberg-type punishment of Iraq as the war aggressor amounts to the same thing as the earlier demands.

In Baghdad, Perez de Cuellar is expected to encounter a rigid demand that the Security Council resolution be fully implemented without any changes.

In addition to calling for a cease-fire, the measure seeks a withdrawal of forces to recognized international boundaries and an exchange of prisoners.

In the weeks leading up to the secretary general's trip, Iraqi warplanes launched attacks on oil targets throughout central and western Iran and on Iranian-related shipping in the Persian Gulf. The message was clear: accept the Security Council resolution or face more of the same.

Iran responded with gunboat attacks on gulf shipping and with heavy artillery fire on Iraqi cities, especially Basra, near the Iranian border.

Iran and Iraq have reported no attacks on gulf shipping since the day before Perez de Cuellar arrived in Tehran. There have been, however, reports of continued ground fighting and artillery shelling of border towns.

Meanwhile, a convoy of three U.S. Navy escorts and two reflagged Kuwaiti tankers continued its voyage out of the gulf, sailing without incident past Farsi Island, where an Iranian Revolutionary Guards naval base is located.